John is twice as old as Mary. The sum of their ages is 21. How old is Mary? Let J = John's age and M = Mary's age. Select the system equations that represents the problem.

J - 2M = 0

M - 2J = 0

J + M = 21

J = M + 2

Question

Sophie

15 August, 16:40

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Answers (1)

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Marlene Ho · Answer 1

J = 2m

J + M = 21

J + M = 21 is your answer.

John is twice as old as Mary. The sum of their ages is 21. How old is Mary? Let J = John's age and M = Mary's age. Select the system equations that represents the problem.J - 2M = 0M - 2J = 0J + M = 21J = M + 2